Theoretical plates resolution enhancement

When packed into chromatography columns, TRIM beads imprinted with Boc-L-Phe were shown to have column efficiencies and separation abilities superior to ground and sieved bulk material [5]. The theoretical plate number was approximately double that obtained with conventional crushed polymer under the same conditions and the resolution of a racemate was also slightly enhanced. The difference, however, was not that great considering the additional preparation time and effort involved. 

The number of theoretical plates and, thus, the separation efficiency, is determined by the length of the separator column. If two separator columns are used in series, the resulting enhancement of separation efficiency leads to a better resolution between ions with similar retention characteristics, with a corresponding increase in retention times. The separator column length also determines the exchange capacity. An increase of the exchange capacity via elongation of the separator column is recommended in all cases where the ion to be analyzed is present in an excess of another component. 

Subsequent important contributions to the field of microchip CE were made early on by Jed Harrison and Andreas Manz, who reported a spectacular enhancement of device performance byredesigning the channel layout and increasing the applied electric fields [11], With an imposed field of 1 kV cm , six fluorescence-tagged amino acids were separated with baseline resolution in 15 s, generating 40 000 to 75 000 theoretical plates. In the improved design, the separation channel length was reduced from 13 to 2.2 cm, utilizing the same cross section as in the previous work. 

Capillary electrophoresis (CE) is a powerful technique that affords rapid, high-resolution separations (10" -10 theoretical plates) while requiring only a few femto-moles of sample. The technique is applicable to a wide range of analytes present in buffered aqueous solution as charged species. The utility of CE, however, is greatly enhanced by MS detection, particularly with a soft ionization technique such as ESI to produce ions even from thermally labile, nonvolatile, polar compounds. 

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